1. Field of the Invention
The present invention relates to a position-detecting apparatus including a plurality of pressure-detecting switches having a detecting nozzle for jetting a fluid supplied from a fluid supply source to a detecting passage toward an object and controlling a flow rate of a fluid supplied from the fluid supply source to a comparing passage, thereby detecting whether or not a pressure in the detecting passage arrives at a prescribed pressure in the comparing passage.
2. Description of the Related Art
A position-detecting apparatus is generally used in order to detect whether or not a workpiece is correctly seated on a seat surface by utilizing the nozzle back pressure. Japanese Laid-Open Patent Publication No. 2000-141166, for example, discloses such a position-detecting apparatus.
As shown in FIG. 6, each of pressure-detecting switches of the position-detecting apparatus comprises a casing 1 and a passage block 2 which are assembled in an integrated manner. Although not shown, a diaphragm and a proximity switch operated by the diaphragm are accommodated in the casing 1. A comparing passage and a detecting passage (not shown), through which the air introduced from a supply port 3 flows in a branched manner while the air is supplied to the diaphragm, are formed in the passage block 2.
Projecting tab plates 4, which protrude in the direction perpendicular to the connecting direction, are formed for the passage block 2. Joiners 5 are integrally installed in a state in which the respective projecting tab plates 4 of the passage blocks 2 to be connected to one another are opposed to one another. The joiners 5 are fastened and fixed to the passage blocks 2 by using bolts 6.
A lead wire-drawing port 7 is formed through a side surface on the connecting side of the casing 1. A lead wire 8 for an electric part such as the proximity switch is drawn from the lead wire-drawing port 7. The lead wires 8 are accumulated in a terminal box 9.
However, conventionally, it is necessary to perform the following wiring operation. That is, the lead wire 8 of each of the casings 1 is introduced into the terminal box 9 through the interior of the adjoining casing 1, and the lead wire 8 is connected to the terminal box 9. Therefore, when the plurality of pressure-detecting switches are connected, or when the pressure-detecting switch is detached, then it is necessary that the other casing 1 adjoining the casing 1 is attached/detached in addition to the casing 1 which is required to be exchanged. As a result, the operation is considerably complicated.
Further, the terminal box 9 can be connected to only one end of each of the plurality of pressure-detecting switches to be connected. Therefore, the place of installation of the entire position-detecting apparatus and the posture of installation are limited. The conventional position-detecting apparatus is inferior in versatile performance.
A general object of the present invention is to provide a position-detecting apparatus which makes it possible to easily and quickly perform the operation for attaching/detaching pressure-detecting switches to be connected to one another.
A principal object of the present invention is to provide a position-detecting apparatus which can be arranged at a variety of places of installation with ease and which is excellent in versatile performance.
According to the present invention, when pressure-detecting switches are mutually attached/detached, it is enough that only first connectors for electric wiring are mutually attached/detached. When the pressure-detecting switch and a terminal board box are attached/detached, it is enough that only first and second connectors for electric wiring are attached/detached. Therefore, it is possible to perform the operation for attaching/detaching the position-detecting apparatus easily and quickly.
Further, according to the present invention, the pressure-detecting switches can be connected to both side sections of the terminal board box with ease. Accordingly, the terminal board box can be arranged at an arbitrary position. The degree of freedom of the installation of the entire position-detecting apparatus is effectively improved. Further, it is possible to apply individual supply pressures to the pressure-detecting switches which are connected to both sides of the terminal board box.
Further, according to the present invention, the first connectors for electric wiring are arranged in openings which are provided at both side sections of the pressure-detecting switch. A projection, which is formed at one side section, is inserted and fitted into the opening which is provided at the other side section. Accordingly, the first connectors for electric wiring can be mutually attached/detached easily and reliably. It is possible to efficiently perform the operation for attaching/detaching the pressure-detecting switch.
Further, according to the present invention, the pressure-detecting switches are connected to one another with a fixing fixture which is arranged for the side sections to be connected to one another. Therefore, the operation for attaching/detaching the pressure-detecting switch is effectively simplified, for example, as compared with a case in which a connecting through bolt is used.
The above and other objects, features, and advantages of the present invention will become more apparent from the following description when taken in conjunction with the accompanying drawings in which a preferred embodiment of the present invention is shown by way of illustrative example.